Advanced Materials Research Vols. 255-260

Abstract: Non-framework cable hoisting erection is a main construction method for long-span arch rib bridge. Geometric nonlinearity is a key problem in the construction simulation of this type of bridge. A general method for construction sequence simulation of long-span arch rib bridge is proposed, and stage-by-stage construction of the Daning River Bridge is simulated. Comparisons of cable forces and finial arch rib geometry between results obtained from actual measurements and those from the simulation analysis are presented. Results showed that the developed method can be used effectively for nonlinear finite-element simulation of long-span arch rib bridge construction.

Abstract: Based on the chain-styled theory, disease mechanism of masonry arch bridge is analyzed in the paper, which indicates that not only the causes of diseases but also results show the complex chain-styled relationship, stages of diseases are divided according to the law of disaster chain, and the measures of chain-cutting, prevention and reinforcement are put forward. Based on the Dongqing Bridge, disease mechanism is analyzed and reinforcement method is proposed according to the idea of chain -cutting disaster mitigation.

Abstract: According to the structural characteristics and the surrounding environment of partially cable-stayed bridge, an asymmetric construction method combinded with support cast-in-place and cantilever casting is applied for main girder construction, based on project of Yuyao cable-stayed bridge. Its basic idea is as follows: One deck section is concreted with brackets in advance, which to offer counterweight for basket construction symmetrically. The technical features and construction key point are described in detail, which provides reference for similar bridge construction.

Abstract: In this paper, completes the selection of preliminary Reactive Powder Concrete (RPC) wind barriers, and on the basis of the theories of the computational fluid dynamics ( CFD), relying on the model-building and analysis platform of FLUENT, 3D models of trains under crosswind with and without wind barriers are built. From the calculation results of the pressure distribution,path lines and aerodynamic forces of model trains under 3D turbulence flows ,the stability of trains under crosswind is analysed ,and the effects of the wind barriers on traffic safety of trains are discussed.The results show that rationa1 design of the wind barriers is able to improve the traffic safety of trains.

Abstract: In order to make much detail and more practical evaluation on structural safety and durability for long-span PC bridges, the condition for prestressing reservation in service stage turns out to be a necessary key index. For the sake of measuring it exactly, an invented instrument named Stretching Force Tester is applied to monitor the effective prestressing force of strand. The precision of this technology is guaranteed by means of amending analogous boundary condition and minimizing test errors through the tool of double-stage differences. Based on comparatively sophisticated prestressing loss method in current code, an evaluation model on attenuation of effective prestress is built up. By means of obtained stress datum on strand, recognition on two types of nominal coefficients for prestress losses is realized and regularities of practical distribution can be simulated simultaneously. The experimental results of a large-scale beam model show that the relative error for cable tension force between test value and standard one is able to meet the needs of engineering use and general principle for effective prestress can be demonstrated. Therefore, it laid the foundation for inspection and evaluation on structural deterioration of existing long-span PC bridges.

Abstract: Based on the hoisting construction feature of large hinge-support tower and field circumstance, the cable hoisting system for Meng-dong river grand bridge at the west of Hunan province is designed. Studying on cable hoisting system design and construction of the CFST arch bridge, the paper takes systematic analysis and calculations on the key construction technology of the CFST arch bridge, and puts it in practice successfully which provides experience for the similar long—span bridge construction of the follow.

Abstract: Through the analysis of the stress distribution in anchorage zone of bridge pylon with different placements of tendon, the placement with the equal coefficient of anti-crack in both sides is proposed. At the same time, several models whose outsides are crossed by tendons at different angles are analyzed. Compared the corresponding cracking loads and cracking place of them, a reasonable angle range is obtained. At last, the vertical attenuation ratio of the prestressing in the anchorage zone under the tendon is analyzed to give the appropriate distance between the adjacent tendons.

Abstract: In order to study the shrinkage and creep effect on improved truss composite arch bridge , this paper analyzed and compared different parameters' influence on the truss composite arch bridge by changing parameters such as shrinkage days, the age of loading, computation theory and diagonal web member forms. It was based on Shiqiaohe bridge, the result showed that shrinkage days and the age of loading were the key parameters; the longer the shrinkage days makes the effects of creep bigger; the longer the age of loading makes the effects of creep smaller. The effect of shrinkage of rigid diagonal web member was larger than that of cables, the applied computation theory has little influence to shrinkage and creep effect on truss composite arch bridge.

Abstract: This paper was based on a bridge project in Chongqing. Finite element software was applied to analyzed the influence of the annual temperature on the pier of continuous rigid-frame bridge with the height parameter change of the pier by analyzing the computing results, this paper summarized the temperature effect on low pier of continuous rigid-frame bridge. It was concluded that the height of the pier was the major factor of the temperature effect on the pier internal forces of the rigid-frame bridge. The lower the pier was, the more obvious the effect of temperature, to some extent, the temperature effect on the pier even exceeded the self-weight effect.

Abstract: The short service life of bridges exerts a negative influence on the operation. The service life of European and American bridges and maintenance is illustrated in this paper. A lot experience has been accumulated which also provide enough data to understand the problem. Some examples are listed in the paper. These data and analysis are of important reference value to understand the bridges in service and the actual service life at present in China.